Koskamo

Postbag MCP

A local MCP server enabling two coding-agent sessions, such as Claude Code and Codex, to exchange messages via native inputs. It facilitates cross-review, split work, and second opinions by allowing agents to join named bags and send letters to each other without copying text between windows.

Package and access

Local package with source-attributed installation metadata. Koskamo does not execute packages during review.

Postbag MCP logo, by parasxosCommunity listingLocal stdioSource reviewed; not executedPublished by parasxos
Vendor documentation

What you can do with it

  • Cross review: Ask Codex to review diffs written by Claude Code
  • Split work: Have Codex write tests while Claude Code writes implementation
  • Second opinion: Ask a stuck agent for a fresh read from the other

Source and maintenance

Community listingRegistry 2.3.0
mcp-registry: io.github.parasxos/postbag@2.3.0Source repository
Maintenance checked

Packages and installation

Source-provided package data. Koskamo has not executed or live-probed this package.

postbag 2.3.0

pypiuvx
postbag package definition
{
  "version": "2.3.0",
  "transport": "stdio",
  "identifier": "postbag",
  "runtimeHint": "uvx",
  "registryType": "pypi",
  "packageArguments": [
    {
      "type": "positional",
      "value": "mcp"
    }
  ],
  "runtimeArguments": [
    {
      "name": "--with",
      "type": "named",
      "value": "postbag[mcp]==2.3.0",
      "description": "The MCP server is the optional mcp extra of the same version."
    }
  ],
  "environmentVariables": [
    {
      "name": "POSTBAG_CODEX",
      "description": "Path to the codex executable for Codex delivery when several are installed."
    }
  ]
}

Tools

Reported by the attributed source; not independently observed by Koskamo.

No tool definitions available.

Connect from your client

Each snippet configures the same source-provided package; replace placeholders before use.

This server is operated by the named third party. Listing and endpoint checks are not an endorsement or a security audit. Review the operator's permissions, terms, and data handling before connecting. How listings are checked and corrected.

Cursor

Merge this local stdio configuration, replace every placeholder environment value, and restart Cursor. Koskamo has not executed this package.
Cursor configuration
{
  "mcpServers": {
    "postbag-mcp": {
      "command": "uvx",
      "args": [
        "postbag==2.3.0",
        "mcp"
      ],
      "env": {
        "POSTBAG_CODEX": "<YOUR_POSTBAG_CODEX>"
      }
    }
  }
}

Cline

Merge this local stdio configuration, replace every placeholder environment value, and restart Cline. Koskamo has not executed this package.
Cline configuration
{
  "mcpServers": {
    "postbag-mcp": {
      "command": "uvx",
      "args": [
        "postbag==2.3.0",
        "mcp"
      ],
      "env": {
        "POSTBAG_CODEX": "<YOUR_POSTBAG_CODEX>"
      }
    }
  }
}

VS Code

Merge this local stdio configuration, replace every placeholder environment value, and restart VS Code. Koskamo has not executed this package.
VS Code configuration
{
  "servers": {
    "postbag-mcp": {
      "type": "stdio",
      "command": "uvx",
      "args": [
        "postbag==2.3.0",
        "mcp"
      ],
      "env": {
        "POSTBAG_CODEX": "<YOUR_POSTBAG_CODEX>"
      }
    }
  }
}

Claude Desktop

Merge this local stdio configuration, replace every placeholder environment value, and restart Claude Desktop. Koskamo has not executed this package.
Claude Desktop configuration
{
  "mcpServers": {
    "postbag-mcp": {
      "command": "uvx",
      "args": [
        "postbag==2.3.0",
        "mcp"
      ],
      "env": {
        "POSTBAG_CODEX": "<YOUR_POSTBAG_CODEX>"
      }
    }
  }
}

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